Cod sursa(job #2742836)
Utilizator | Cristian Chris.s | Data | 21 aprilie 2021 22:52:47 |
---|---|---|---|
Problema | Fractii | Scor | 100 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva de probleme | Marime | 0.54 kb |
#include <iostream>
#include <fstream>
using namespace std;
int ciur[10000005];
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int main()
{
int n;
fin>>n;
ciur[1]=1;
for(int i=2;i<=n;i++)
{
ciur[i]=i-1;
}
for(int i=2;i<=n;i++)
{
for(int j=i+i;j<=n;j+=i)
{
ciur[j]-=ciur[i];
}
}
long long sum=0;
for(int i=2;i<=n;i++)
{
sum+=ciur[i];
}
sum*=2;
sum++;
fout<<sum<<'\n';
return 0;
}